In recent years a great amount of interest has focused on the role of dopamine-glutamate interactions in the control of neural plasticity, learning and memory, and addiction. These two neurotransmitter systems are found widely distributed in many regions of cortex, limbic system, and basal ganglia, where they appear to play an integrative role in motivational and associative information processing. It is currently believed that coordinated neural signaling of these systems, particularly through the dopamine D1 and glutamate N-methyI-D-aspartate (NMDA) receptors, is a critical event in triggering intracellular transductional and transcriptional cascades that lead to long-term changes in gene expression, synaptic plasticity, and ultimately behavior. Addictive drugs also induce long-term neuroadaptations at the structural, cellular, molecular, and genomic levels, primarily through their impact on dopaminergic and glutamatergic circuits. Such drug-induced neuroadaptations may contribute to abnormal information processing and behavior, resulting in poor decision-making, loss of control, and compulsivity that characterized addiction. Thus, further information regarding the normal behavioral role of dopamine- and glutamate-mediate neural networks may help to shed light on the nature of addiction and its treatment. In this research project, the role of glutamate- and dopamine-coded neural circuitry in the control of appetitive instrumental learning will be explored. Using anatomical, molecular, and behavioral approaches, we will test the hypothesis that NMDA- and Dl-receptor mediated plasticity within multiple nodes of a neural network controls new adaptive motor learning.